Solutions for safety communication to be used in industrial fields are currently sought. In particular, industrial control systems are required to maintain a prescribed or higher level of integrity of information transferred via a network in order to secure the safety of workers, avoid threats to environment and prevent the occurrence of safety-related problems.
In order to satisfy such integrity requirements, industrial control systems are required to treat problems about corruption, unintended repetition, incorrect sequence, loss, unacceptable delay, insertion, masquerade and addressing.
Regarding the problem of corruption, industrial control systems should be able to determine whether an error occurs in data being transferred, with a prescribed or higher level of probability.
Regarding the problem of unintended repetition, industrial control systems should be able to determine whether data repetition which is not maliciously intended by a person occurs normally, with a prescribed or higher level of probability.
Regarding the problem of incorrect sequence, industrial control systems should be able to determine whether a sequence of transmission of data is changed, with a prescribed or higher level of probability.
Regarding the problem of loss, industrial control systems should be able to determine whether a part of transmitted data is damaged, with a prescribed or higher level of probability.
Regarding the problem of unacceptable delay, industrial control systems should be able to determine whether an unacceptable delay occurs in transmission of data, with a prescribed or higher level of probability.
Regarding the problem of insertion, industrial control systems should be able to determine whether unintended data is inserted while transmitting data, with a prescribed or higher level of probability.
Regarding the problem of masquerade, industrial control systems should be able to determine whether data is changed maliciously by a person, with a prescribed or higher level of probability.
Regarding the problem of addressing, industrial control systems should be able to determine whether data is transmitted to a right receiver, with a prescribed or higher level of probability.
IEC 61508 represents a probability of error occurrence using SIL as shown in table 1 below.
TABLE 1SIL4>=10−9, <10−8SIL3>=10−8, <10−7SIL2>=10−7, <10−6SIL1>=10−6, <10−5
For example, to satisfy SIL3, the probability of error occurrence should satisfy 10−9.
However, it is difficult for current Ethernet frame structures to satisfy the integrity requirements of industrial control systems.